Facile synthesis of hierarchical carpet-like WO3 microflowers for high NO2 gas sensing performance

The hierarchical carpet-like WO3 microflowers were synthesized via a facile one-step hydrothermal method by using oleic acid as a oriented growth reagent. The as-synthesized WO3 microflowers show a triclinic crystal structure and are basically hierarchical assemblies of carpet-like nanosheets made up of the subunit of bundle-like nanowires. Based on the morphology evolution process, a possible crystal growth and nanostructure assembling mechanism were proposed. The prepared WO3 microflower sensor exhibits a gas sensing response of about 228 when exposed to 10 ppm of toxic NO2 gas at 200 °C.